Slot all your attacks with 3 Damage and targeting drone with 3 tohitbuff. With targetting drone you can get away without slotting accuracy in attacks in my opinion but this build really needs a slotting rework.
I'd say the slots in the build below are what I'd call the minimum sort of slotting requirements for the build and leaves with about another 20 slots to put in, mostly recharges of your choosing depending on which powers you want to use more often.
Exported from version 1.5C of CoH Planner
http://joechott.com/coh
Archetype: Blaster
Primary Powers - Ranged : Fire Blast
Secondary Powers - Support : Devices
01 : Web Grenade acc(01)
01 : Flares dam(01) dam(3) dam(3)
02 : Fireblast dam(02) dam(5) dam(5) endred(9)
04 : Caltrops slw(04) slw(13) slw(23)
06 : Fireball dam(06) dam(7) dam(7) endred(9)
08 : Swift runspd(08)
10 : Targeting Drone thtbuf(10) thtbuf(11) thtbuf(11) endred(13)
12 : Hover fltspd(12)
14 : Fly fltspd(14) fltspd(15) fltspd(15) endred(17) endred(17)
16 : Health hel(16)
18 : Fire Breath dam(18) dam(19) dam(19) endred(21)
20 : Stamina endrec(20) endrec(21) endrec(23)
22 : Cloaking Device endred(22)
24 : Blaze dam(24) dam(25) dam(25)
26 : Blazing Bolt dam(26) dam(27) dam(27) endred(33) inttim(37)
28 : Trip Mine dam(28) dam(29) dam(29) acc(40)
30 : Rain of Fire dam(30) dam(31) dam(31) endred(31)
32 : Inferno dam(32) dam(33) dam(33)
35 : Time Bomb dam(35) dam(36) dam(36) acc(37)
38 : Auto Turret dam(38) dam(39) dam(39) acc(39)
41 : Bonfire acc(41)
44 : Char hlddur(44) hlddur(45) hlddur(45)
47 : Fire Shield damres(47) damres(48) damres(48) endred(48)
49 : Rise of the Phoenix recred(49)
-------------------------------------------
01 : Brawl enhancement(01)
01 : Sprint enhancement(01)
02 : Rest enhancement(02)
Just my two inf, but I think both of you are missing a trick here: Teleport Foe.
"Telemining" your opponents onto a big pile of bangy goodness turns your Trip Mines from a "passive" attack - where you have to coax enemies on to your mines - to an active one, where you can safely dispose of Malta Sappers, Voids and other nastiness easily.
With four mines and a successful hit roll, you can also safely dispose of most player villains except Energy Stalkers. Even most Brutes will succumb with six or seven. Telemining's a different kind of villain hunting - rather than chasing them into their territory, find a popular battle spot and wait for them to come to you.
- Take TP Foe at either 26 or 30 (giving you access to it in Siren's.)
- Drop Time Bomb and shift Rain Of Fire to 35 (Time Bomb may have superior damage but is trickier to use, especially in teams. Two Trip Mines will give better damage).
- Attack sequence:
Trip Mine
Caltrops (stops them running straight off)
TP Foe
Fire Blast (finish them!)
Is it time for the dance of joy yet?
Given my main, it's hardly a surprise that I'd agree on fun side of fire/dev blasters but I'll make a couple of suggestions, if you want.
Firstly, as Jersey pointed out, make sure to 3-slot your attacks for damage and targeting drone for tohit buffs.
Secondly, I wouldn't recommend flares - quick but the damage output isn't all that great in comparison to the rest of the set (it is, IMO, an easily skippable power). Not a huge fan of rain of fire either (your powers are based on AoE and RoF makes the mobs scatter like particularly flightly pigeons seeing a cat) but it can be combined somewhat successfully with caltrops if you're game for it.
Aside from the above 2 powers, Jersey's posted build looks good - though I'd highly recommend adding rech to your attacks and thinking about picking up hasten.
Never tried DreamWeaver's TP suggestion but I can see how effective it would be if it catches your fancy.
And Cloak + Timebomb in a large group of enemies works really well... when soloing, at least...
Anyway, that's my 2 inf - discard as you see fit and have fun. 
P.S. Do mind the aggro, won't you? 
Good idea to listen to the power advice above ^^ I just changed the slotting on the powers you already picked since I was too lazy to give power advice Also, don't now enough about devices to really comment.
thanks for the advice, but from what I heard Hasten isnt required any more and TP Foe has the most stupid of accuracy if there was anything I would take in TP it would be TP friend and finally I was only thinking of the enhancing upgrade as its not as its used to before I6 or I5 I think....
Thanks again for the advice ^^
TP Foe works fine - can pick up any minion and 90% of Lieutenants with 1 or 2 Acc slots.
Bosses are immune, but they're much more vulnerable with minions stripped away.
Oh, did I mention you don't have to be in line of sight when you TP a foe?
Is it time for the dance of joy yet?
True, hasten isn't nearly as uber as it was 
but, if you've got the space for it, I'd consider picking it up for those moments when you hit build-up and wanted to spam blaze at an EB or some such .
That said, I have hasten because I wanted SS and it's sooo much handier than flurry.
okie taken in from your advice this is what I made up (whilst in college) I decided to remake my blaster he's already lvl 5 now though ^^
[/b]Archetype: Blaster
Primary: Fire Blast
Secondary: Devices
---------------------------------------------
01) --> Flares==> Dmg(1)Dmg(3)Dmg(3)
01) --> Web Grenade==> Acc(1)
02) --> Fire Ball==> Dmg(2)Dmg(5)Dmg(5)EndRdx(9)EndRdx(9)
04) --> Caltrops==> Slow(4)Slow(7)Slow(7)
06) --> Swift==> Run(6)
08) --> Fire Breath==> Dmg(8)Dmg(11)Dmg(11)EndRdx(13)
10) --> Targeting Drone==> TH_Buf(10)TH_Buf(13)TH_Buf(15)EndRdx(15)
12) --> Hover==> Fly(12)
14) --> Fly==> Fly(14)Fly(17)Fly(17)
16) --> Health==> Heal(16)Heal(19)Heal(19)
18) --> Blaze==> Dmg(18)Dmg(21)Dmg(21)
20) --> Stamina==> EndMod(20)EndMod(23)EndMod(23)
22) --> Cloaking Device==> EndRdx(22)
24) --> Smoke Grenade==> TH_DeBuf(24)Acc(25)EndRdx(25)
26) --> Blazing Bolt==> Dmg(26)Dmg(27)Dmg(27)EndRdx(29)IntRdx(29)
28) --> Trip Mine==> Dmg(28)Dmg(31)Dmg(31)Acc(31)
30) --> Teleport Foe==> Acc(30)
32) --> Inferno==> Dmg(32)Dmg(33)Dmg(33)
35) --> Time Bomb==> Dmg(35)Dmg(36)Dmg(36)Acc(36)
38) --> Auto Turret==> Dmg(38)Dmg(39)Dmg(39)Acc(39)
41) --> Bonfire==> Dmg(41)
44) --> Char==> Hold(44)Hold(45)Hold(45)
47) --> Fire Shield==> DmgRes(47)DmgRes(48)DmgRes(48)EndRdx(48)
49) --> Rise of the Phoenix==> Rechg(49)Rechg(50)Rechg(50)DisDur(50)
EDIT: No I dont mind the aggro and flares are pretty good power attack I reckon, tried making a new char with fire blast didnt go to well so restarted with Shadow Nightfire
I'm a fire/dev blaster myself so I think you're going to have fun, a few points to make however.
If you're going to insist on flares, it only needs 5 slots, 3 damage, 1 accurace and 1 range increase. All your other main attacks (like fire blast, blaze, snipe) should be 6 slotted with 3 damage, 1 accuracy and either 2 end. red., 2 recharge or one of either, depending on it's cost. (For example, fire blast is better with 2 end. red. because it's endurance cost is high but recharges pretty quicly on its own anyway.)
Personally, I avoided Rain of Fire and Fire Breath as they really aren't that good - they spread mobs, don't do that much damage and aren't really main attacks. I also avoided Caltrops because although they do slow enemies down and help in PvP to prevent AS, they also scatter mobs, cost a lot, have long recharge even with SO's and aren't that useful in PvE.
Time Bomb is an interesting choice. I didn't take it because it has a 15second period before it blows, in that time you've either killed your enemy or it's moved, but go for it if you like.
Also, in my first build I took Swift, Health and Stamina in that power pool, but I really didn't find that much of a difference with Health. I have SJ and acrobatics which gives me some resistance to holds, and so decided to opt for Hurdle instead. Obviously you have fly not SJ, but just thought this might be something to consider.
As for your epic, I debated for a long time whether to take the fire epic or munitions, and eventually opted for Munitions. It provides you with a good hold (waaaay better than web granade) an armour (essential as a blaster) and a really good missile for your last power (as far as I can remember.)
It's up to you how you play you're blaster - good luck! Hope this was helpful
[ QUOTE ]
If you're going to insist on flares, it only needs 5 slots, 3 damage, 1 accurace and 1 range increase. All your other main attacks (like fire blast, blaze, snipe) should be 6 slotted with 3 damage, 1 accuracy and either 2 end. red., 2 recharge or one of either, depending on it's cost.
[/ QUOTE ]
Largely agree with this though I still wouldn't recommend flares.
[ QUOTE ]
Personally, I avoided Rain of Fire and Fire Breath as they really aren't that good - they spread mobs, don't do that much damage and aren't really main attacks.
[/ QUOTE ]
Can't say I agree with this on Fire Breath. First, I have never found it a power that causes mobs to scatter and, secondly, it does very decent damage indeed. And, while the range of Fire Breath is poor, it is a cone attack and I would certainly regard it as a main attack.
With regards to Time Bomb, see my previous suggestion - works quite well.
[ QUOTE ]
It provides you with a good hold (waaaay better than web granade) an armour (essential as a blaster)
[/ QUOTE ]
/pedant
Web grenade is immob, not a hold
/pedant
Body Armour is an auto res power giving 12.5% S/L res, IIRC. Decent for an auto but not spectacular.
LRM is very good though.
Hmm... I seem to be coming across quite defensively, I apologise if this is too much but I really love this powerset combination.
[ QUOTE ]
Slot all your attacks with 3 Damage and targeting drone with 3 tohitbuff. With targetting drone you can get away without slotting accuracy in attacks in my opinion but this build really needs a slotting rework.
[/ QUOTE ]
No....Got a fire/dev myself 1 acc slot in all tactics runnin and 3 to hit buffs in target drone..you still miss a lot when fighting 2-3+...
dev blasters are great in combination with tanks btw...let the tank agro place a trip mine in the middle of the group..then aim+fireball 
Hot_Head it's ok! Fire/Dev's RAWK I quite agree!!!
\m/
Hey I love being a fire blaster always has always will so I thought I might try out the devices side so far pretty fun caltrops and Fireball are a fun mix!
sooo heres a build I made from my current character on what I plan to do with the guy...
---------------------------------------------
Exported from Ver: 1.7.6.0 of the CoH_CoV Character Builder
---------------------------------------------
Name: Seika
Archetype: Blaster
Primary: Fire Blast
Secondary: Devices
---------------------------------------------
01) --> Flares==> Dmg(1)Acc(3)Rechg(3)
01) --> Web Grenade==> Acc(1)Immob(5)Rechg(5)
02) --> Fire Blast==> Dmg(2)Acc(7)Rechg(7)
04) --> Caltrops==> Dmg(4)Slow(9)Rechg(9)
06) --> Fire Ball==> Dmg(6)Acc(11)Rechg(11)
08) --> Swift==> Run(8)
10) --> Targeting Drone==> TH_Buf(10)EndRdx(13)Rechg(13)
12) --> Hover==> DefBuf(12)
14) --> Fly==> Fly(14)
16) --> Health==> Heal(16)
18) --> Fire Breath==> Dmg(18)Acc(19)Range(19)
20) --> Stamina==> EndMod(20)
22) --> Cloaking Device==> DefBuf(22)EndRdx(23)Rechg(23)
24) --> Blaze==> Dmg(24)Acc(25)Rechg(25)
26) --> Blazing Bolt==> Dmg(26)IntRdx(27)Acc(27)Range(29)
28) --> Trip Mine==> Dmg(28)Acc(29)EndRdx(31)KB_Dist(31)Rechg(34)
30) --> Rain Of Fire==> Dmg(30)EndRdx(31)Range(33)Rechg(33)
32) --> Inferno==> Dmg(32)Acc(33)EndRdx(34)Rechg(34)
35) --> Time Bomb==> Dmg(35)Acc(36)EndRdx(36)KB_Dist(36)Rechg(37)
38) --> Auto Turret==> Dmg(38)Acc(39)EndRdx(39)Rechg(39)
41) --> Bonfire==> Dmg(41)EndRdx(42)KB_Dist(42)Range(42)Rechg(43)
44) --> Char==> Dmg(44)Acc(45)EndRdx(45)Hold(45)Rechg(46)Range(46)
47) --> Fire Shield==> DmgRes(47)EndRdx(48)Rechg(48)
49) --> Rise of the Phoenix==> Dmg(49)DisDur(50)EndMod(50)Rechg(50)
---------------------------------------------
01) --> Sprint==> Empty(1)
01) --> Brawl==> Empty(1)
02) --> Rest==> Empty(2)
01) --> Defiance==> Empty(1)
---------------------------------------------
Thx for the help!